Schizophrenia (SCZ) and bipolar disorder-I (BPD) have many similarities, but they have notably different emotional response profiles to appetitive stimuli, and these are present even among clinically stable patients. The goal of this R21 application is to apply current affective neuroscience methods to understand the underlying processes for these different emotional response profiles. We will test hypotheses that stable outpatients with SCZ and euthymic BPD-I patients with a history of psychosis will demonstrate opposite central and peripheral nervous system responses to rewarding stimuli during two types of tasks: affective chronometry, which refers to the temporal parameters (e.g., anticipation, offset) of emotional responding, and motivational engagement, which refers to mobilization of physiological response systems during impending rewards and punishments. 35 SCZ outpatients, 35 euthymic BPD outpatients, and 35 matched healthy controls will complete the two types of paradigms while simultaneous ERP and startle eye blink responses are recorded. Affective chronometry will be measured with a passive emotional picture viewing task with startle probes before, during, and after picture presentation. Motivational engagement will be measured with an active motivational gradient task, in which cues signaling reward or punishment appear to loom progressively closer to the viewer. We predict SCZ patients will demonstrate hypo-reactivity and BPD patients will show hyper-reactivity for specific physiological responses to positive stimuli. Identification of emotional disturbances that are uniquely associated with SCZ and BPD would have direct implications for treatment development and identification of novel endophenotypes. PUBLIC HEALTH RELEVANCE: Schizophrenia (SCZ) and bipolar disorder-I (BPD) are two of the most severely disabling psychiatric disorders, and recent evidence suggests that notably different emotional response abnormalities contribute to poor outcome within each disorder. The goal of this R21 exploratory grant application is to apply affective neuroscience methods to test the hypothesis that stable outpatients with SCZ or BPD-I with a history of psychosis (in a euthymic mood state) will demonstrate differential central and peripheral nervous system responses during tasks that index affective chronometry and motivational engagement. Identification of emotional disturbances that are uniquely associated with each disorder would have direct implications for treatment development and novel emotional endophenotypes.